Talk_id  Date  Speaker  Title 
31520

Monday 12/19 2:00 PM

Jing Zhou, Penn State University

Application of KAM Theory in the FermiUlam Models (cont'd)
 Jing Zhou, Penn State University
 Application of KAM Theory in the FermiUlam Models (cont'd)
 12/19/2022
 2:00 PM  3:00 PM
 C304 Wells Hall
 Huyi Hu (hhu@msu.edu)
In this talk I’ll briefly introduce the Fermi acceleration problem and some existing results on the subject. In particular, I’ll discuss how KAM theory has been applied in several variants of the FermiUlam models. I’ll also discuss some open problems in this direction.

31514

Monday 1/9 4:10 PM

Anna Weigandt, Massachusetts Institute of Technology

Combinatorial Aspects of Determinantal Varieties
 Anna Weigandt, Massachusetts Institute of Technology
 Combinatorial Aspects of Determinantal Varieties
 01/09/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
Schubert calculus has its origins in enumerative questions asked by the geometers of the 19th century, such as “how many lines meet four fixed lines in threespace?” These problems can be recast as questions about the structure of cohomology rings of geometric spaces such as flag varieties. Borel’s isomorphism identifies the cohomology of the complete flag variety with a simple quotient of a polynomial ring. Lascoux and Schützenberger (1982) defined Schubert polynomials, which are coset representatives for the Schubert basis of this ring. However, it was not clear if this choice was geometrically natural. Knutson and Miller (2005) provided a justification for the naturality of Schubert polynomials via antidiagonal Gröbner degenerations of matrix Schubert varieties, which are generalized determinantal varieties. Furthermore, they showed that preexisting combinatorial objects called pipe dreams govern this degeneration. In this talk, we study the dual setting of diagonal Gröbner degenerations of matrix Schubert varieties, interpreting these limits in terms of the “bumpless pipe dreams” of Lam, Lee, and Shimozono (2021). We then use the combinatorics of Ktheory representatives for Schubert classes to compute the CastelnuovoMumford regularity of matrix Schubert varieties, which gives a bound on the complexity of their coordinate rings.

31527

Tuesday 1/10 2:30 PM


G&T Seminar Organizational Meeting

 G&T Seminar Organizational Meeting
 01/10/2023
 2:30 PM  3:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
No abstract available.

31521

Tuesday 1/10 4:10 PM

Nathaniel Bottman, Max Planck Institute

What analysis, combinatorics, and quilted spheres can tell us about symplectic geometry
 Nathaniel Bottman, Max Planck Institute
 What analysis, combinatorics, and quilted spheres can tell us about symplectic geometry
 01/10/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
A central tool for studying symplectic manifolds is the Fukaya category. In this talk, I will describe my program to relate the Fukaya categories of different symplectic manifolds. The key objects are "witch balls", which are coupled systems of PDEs whose domain is the Riemann sphere decorated with circles and points, and "2associahedra", the configuration spaces of these domains. I will describe applications to symplectic geometry and algebraic geometry, and highlight the role of degenerating families of elliptic PDEs.

31519

Wednesday 1/11 4:10 PM

Aver St. Dizier, University of Illinois

A Polytopal View of Schubert Polynomials
 Aver St. Dizier, University of Illinois
 A Polytopal View of Schubert Polynomials
 01/11/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
Schubert polynomials are a family of multivariable polynomials whose product can be used to solve problems in enumerative geometry. Despite their many known combinatorial formulas, there remain mysteries surrounding these polynomials. I will describe Schubert (and the special case of Schur) polynomials with a focus on polytopes. From this perspective, I will address questions such as vanishing of Schubert coefficients, relative size of coefficients, and interesting properties of their support. Time permitting, I'll talk about my current work on generalizing the Gelfand–Tsetlin polytope, and its connections with representation theory and Bott–Samelson varieties.

31529

Thursday 1/12 2:30 PM

Simon Foucart, Texas A&M University

ZOOM TALK (Passcode: the smallest prime > 100 ): Three uses of semidefinite programming in approximation theory
 Simon Foucart, Texas A&M University
 ZOOM TALK (Passcode: the smallest prime > 100 ): Three uses of semidefinite programming in approximation theory
 01/12/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Mark A Iwen (iwenmark@msu.edu)
In this talk, modern optimization techniques are publicized as fitting computational tools to attack several extremal problems from Approximation Theory which had reached their limitations based on purely analytical approaches. Three such problems are showcased: the first problemminimal projectionsinvolves minimization over measures and exploits the moment method; the second problemconstrained approximationinvolves minimization over polynomials and exploits the sumofsquares method; and the third problemoptimal recovery from inaccurate observationsis highly relevant in Data Science and exploits the Sprocedure. In each of these problems, one ends up having to solve semidefinite programs.

31511

Thursday 1/12 4:10 PM

Demetre Kazaras, Duke University

The geometry of scalar curvature and mass in general relativity
 Demetre Kazaras, Duke University
 The geometry of scalar curvature and mass in general relativity
 01/12/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
In general relativity, the space we inhabit is modeled by a Riemannian manifold. The fundamental restriction this theory places upon spatial geometry is a lower bound on this manifold's scalar curvature. It is an important problem in pure geometry to understand the geometric and topological features of this condition. For instance, if a manifold has positive scalar curvature, what may we conclude about the lengths of its curves, the areas of its surfaces, and the topology of the underlying manifold? I will explain many results (originally proven by SchoenYau and GromovLawson) in this direction, and sketch proofs by analyzing objects I call 'spacetime harmonic functions.' Leveraging these new ideas, I will also describe progress on geometric versions of the following questions: How flat is a gravitational system with little total mass? How can we tell when matter will coalesce to form a black hole?

31528

Friday 1/13 4:10 PM

Alexander Watson, University of Minnesota

Mathematics of novel materials from atomic to macroscopic scales
 Alexander Watson, University of Minnesota
 Mathematics of novel materials from atomic to macroscopic scales
 01/13/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
Materials' electronic properties arise from the complex dynamics of electrons flowing through the material. These dynamics are quantum mechanical and present many surprising phenomena without classical analogues. I will present analytical and numerical work clarifying these dynamics in three novel materials which have attracted intense theoretical and experimental attention in recent years: graphene, the first ``2D'' material, whose electronic properties can be captured by an effective Dirac equation, topological insulators, whose edges host surprising oneway edge currents, and twisted bilayer graphene, an aperiodic material whose properties can be captured by an effective system of Dirac equations with periodic coefficients. I will then present ongoing and future work focused on further clarifying the properties of twisted bilayer graphene, which was recently shown to superconduct when twisted to the ``magic'' twist angle 1 degree.

31510

Tuesday 1/17 4:10 PM

Cesar Cuenca, Harvard University

Random matrices and random partitions at varying temperatures
 Cesar Cuenca, Harvard University
 Random matrices and random partitions at varying temperatures
 01/17/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
I will discuss the globalscale behavior of ensembles of random matrix eigenvalues and random partitions which depend on the "inverse temperature" parameter beta. The goal is to convince the audience of the effectiveness of the moment method via Fourierlike transforms in characterizing the Law of Large Numbers and Central Limit Theorems in various settings. We focus on the regimes of high and low temperatures, that is, when the parameter beta converges to zero and infinity, respectively. Part of this talk is based on joint projects with F. BenaychGeorges  V. Gorin, and M. Dolega  A. Moll.

31524

Wednesday 1/18 4:10 PM

Charles Ouyang, UMass Amherst

Compactifications of Hitchin components
 Charles Ouyang, UMass Amherst
 Compactifications of Hitchin components
 01/18/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
Hitchin components are natural generalizations of the classical Teichmüller space. In the setting of SL(3,R), the Hitchin component parameterizes the holonomies of convex real projective structures, which are related to hyperbolic affine spheres. By studying Blaschke metrics, which are Riemannian metrics associated to hyperbolic affine spheres, along with their limits, we obtain a compactification of the SL(3,R)Hitchin component. We show the boundary objects are hybrid structures, which are in part flat metric and in part laminar. These hybrid objects are natural generalizations of measured laminations, which are the boundary objects in Thurston's compactification of Teichmüller space.

31530

Thursday 1/19 2:30 PM

Madeleine Udell, Stanford University

ZOOM TALK (Passcode: the smallest prime > 100 ): Low rank approximation for faster optimization
 Madeleine Udell, Stanford University
 ZOOM TALK (Passcode: the smallest prime > 100 ): Low rank approximation for faster optimization
 01/19/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Mark A Iwen ()
Low rank structure is pervasive in realworld datasets. This talk shows how to accelerate the solution of fundamental computational problems, including eigenvalue decomposition, linear system solves, composite convex optimization, and stochastic optimization (including deep learning), by exploiting this low rank structure. We present a simple method based on randomized numerical linear algebra for efficiently computing approximate top eigendecompositions, which can be used to replace large matrices (such as Hessians and constraint matrices) with low rank surrogates that are faster to apply and invert. The resulting solvers for linear systems (NystromPCG), composite convex optimization (NysADMM), and deep learning (SketchySGD) demonstrate strong theoretical and numerical support, outperforming stateoftheart methods in terms of speed and robustness to hyperparameters.

31518

Thursday 1/19 4:10 PM

March Tian Boedihardjo, ETH Zurich

Freeness and matrices
 March Tian Boedihardjo, ETH Zurich
 Freeness and matrices
 01/19/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
I will begin by giving some background on Free Probability motivated by the freeness in free groups. I will then demonstrate how Free Probability can be used to obtain a sharp nonasymptotic random matrix estimate for general use. This talk will be concluded by a recent application of our result to the Matrix Spencer Conjecture. Joint work with Afonso Bandeira and Ramon van Handel.

31552

Friday 1/20 3:00 PM

Fan Yang, Michigan State University

Lorenz attractor and singular flows: expansivity, entropy, and equilibrium states
 Fan Yang, Michigan State University
 Lorenz attractor and singular flows: expansivity, entropy, and equilibrium states
 01/20/2023
 3:00 PM  5:00 PM
 C304 Wells Hall
 Fan Yang (yangfa31@msu.edu)
No abstract available.

31512

Monday 1/23 4:10 PM

Zhongshan An, University of Michigan

Geometric boundary conditions for the Einstein equations and quasilocal mass
 Zhongshan An, University of Michigan
 Geometric boundary conditions for the Einstein equations and quasilocal mass
 01/23/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
The Einstein equations are the most fundamental equations for spacetimes in general relativity. They relate the geometry (curvatures) of a spacetime with its physical property. When a spacetime has nonempty boundary, it is natural to ask what geometric boundary conditions are wellposed for the Einstein equations. The investigation of geometric boundary conditions both gives rise to interesting geometric PDE problems in differential geometry, and also plays an important role in the study of quasilocal mass for compact spacetimes in general relativity. In this talk, we will discuss geometric boundary conditions for the vacuum Einstein equations, from both the hyperbolic and elliptic aspects. Furthermore, we will talk about applications of these geometric boundary value problems in the construction of quasilocal mass.

31551

Tuesday 1/24 1:00 PM

Vince Melfi, MSU; Jenny Green, MSU; John Keane, MSU

Fostering a Culture of Instructional Development in the Department of Statistics and Probability: Our Journey with FirstYear Graduate Teaching Assistants
 Vince Melfi, MSU; Jenny Green, MSU; John Keane, MSU
 Fostering a Culture of Instructional Development in the Department of Statistics and Probability: Our Journey with FirstYear Graduate Teaching Assistants
 01/24/2023
 1:00 PM  2:30 PM
 115 Erickson Hall
 Lisa Keller (kellerl@msu.edu)
How do we support graduate students to teach introductory statistics classes, which themselves are undergoing dramatic transformation? In this talk, we will get to engage with
lessons learned and questions still unanswered as we embarked on the journey of developing an instructional mentoring program for the Department of Statistics and Probability.

31540

Wednesday 1/25 3:00 PM

Wlodzimierz Bryc, University of Cincinnati

Stationary measures of the KardarParisiZhang equation and their limits
 Wlodzimierz Bryc, University of Cincinnati
 Stationary measures of the KardarParisiZhang equation and their limits
 01/25/2023
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Konstantin Matetski (matetski@msu.edu)
I will overview recent results of [Corwin and Knizel, 2021] on the existence of stationary measures for the KPZ equation on an interval and [Barraquand and Le Doussal, 2022], [B.KuznetsovWangWesolowski, 2022] who found two different probabilistic descriptions of the stationary measures as a Markov process and as a measure with explicit RadonNikodym derivative with respect to the Brownian motion. The Markovian description leads to rigorous proofs of some of the limiting results claimed in [Barraquand and Le Doussal, 2022]. I shall discuss how the stationary measures of the KPZ equation on [0,L] behave at large scale as L goes to infinity which according to [Barraquand and Le Doussal, 2022] depending on the normalization, should correspond to stationary measures of a hypothetical KPZ fixed point on [0,1], to the stationary measure for the KPZ equation on the halfline, and to the stationary measure of a hypothetical KPZ fixed point on the halfline.
The talk is based mostly on a joint work with Alexey Kuznetsov (ALEA 2022).

31525

Wednesday 1/25 3:00 PM

Yibo Gao, University of Michigan

CANCELLED: Symmetric structures in the strong Bruhat order
 Yibo Gao, University of Michigan
 CANCELLED: Symmetric structures in the strong Bruhat order
 01/25/2023
 3:00 PM  3:50 PM
 C304 Wells Hall
 Bruce E Sagan (bsagan@msu.edu)
The Bruhat order encodes algebraic and topological information of Schubert varieties in the flag manifold and possesses rich combinatorial properties. In this talk, we discuss three interrelated stories regarding the Bruhat order: selfdual Bruhat intervals, BilleyPostnikov decompositions and automorphisms of the Bruhat graph. This is joint work with Christian Gaetz.

31550

Wednesday 1/25 3:30 PM

Katie Lewis, University of Washington

Disability Equity in Mathematics Education: Accessibility, Remediation, and CompensationAbstract
 Katie Lewis, University of Washington
 Disability Equity in Mathematics Education: Accessibility, Remediation, and CompensationAbstract
 01/25/2023
 3:30 PM  5:00 PM
 252 EH
(Virtual Meeting Link)
 Lisa Keller (kellerl@msu.edu)
Equity in mathematics education research has only recently begun to consider students with disabilities. In this talk, I focus specifically on students with mathematics disabilities – students who have a neurological difference in how their brains process numerical information. Prior research on mathematics disabilities (i.e., dyscalculia) has predominantly taken up a deficit frame, documenting the ways in which students with dyscalculia are deficient in terms of speed and accuracy. In my work, I argue that this deficit orientation is problematic, and I offer an alternative. I take up an explicitly antideficit framing and draw upon sociocultural learning theories and Disability Studies to orient my work. In this talk I use multiple case studies to explore ideas about accessibility, remediation, and compensation across a range of mathematical topics. This antideficit work provides an alternative vantage point to understand disability in mathematics education and suggests avenues to work towards equity. I close by considering ways that mathematics education equity research can be in service of and in partnership with the populations that we study. Zoom option: https://msu.zoom.us/j/95059549382 Passcode: PRIME

31531

Monday 1/30 4:00 PM

Lucas Hall, MSU

Approximately Finite Dimensional C*algebras
 Lucas Hall, MSU
 Approximately Finite Dimensional C*algebras
 01/30/2023
 4:00 PM  5:30 PM
 C517 Wells Hall
 Brent Nelson (banelson@msu.edu)
I’ll tour through the study of finite dimensional C*algebras and homomorphisms between them, and use this as a basis to define and study approximately finite dimensional (AF) algebras.

31559

Tuesday 1/31 3:00 PM

Theodore Voronov, University of Manchester

From homotopy Lie brackets to thick morphisms of supermanifolds and nonlinear functionalalgebraic duality (NOTE UNUSUAL DAY)
 Theodore Voronov, University of Manchester
 From homotopy Lie brackets to thick morphisms of supermanifolds and nonlinear functionalalgebraic duality (NOTE UNUSUAL DAY)
 01/31/2023
 3:00 PM  4:00 PM
 C204A Wells Hall
 Michael Shapiro (mshapiro@msu.edu)
I will give a motivation for homotopy Lie brackets and the corresponding morphisms preserving brackets "up to homotopy" (more precisely, for Linfinity morphisms and Linfinity algebras), and show how to describe them using supergeometry. So, instead of a single Poisson or Lie bracket, there is a whole sequence of operations with n arguments, n=1,2,3,..., satisfying a linked infinite sequence of identities replacing the familiar Jacobi identity for a Lie bracket; and, instead of a morphism as a linear map mapping a bracket to a bracket, there is a sequence of multilinear mappings mixing brackets with different numbers of arguments, and, in particular, the binary bracket is preserved only up to an (algebraic) homotopy. Geometrically, such a sequence of multilinear mappings assembles into one nonlinear map of supermanifolds.
For the case of homotopy brackets of functions ("higher Poisson" or "homotopy Poisson" structure), this leads us to the question about a natural construction of nonlinear mappings between algebras of smooth functions generalizing the usual pullbacks. I discovered such a construction some years ago. These are "thick morphisms" of (super)manifolds generalizing ordinary smooth maps. From a more general perspective, we arrive in this way at a nonlinear analog of the classical functionalalgebraic duality between spaces and algebras.

31557

Wednesday 2/1 3:00 PM

Stephen Lacina, University of Oregon

Maximal Chain Descent Orders
 Stephen Lacina, University of Oregon
 Maximal Chain Descent Orders
 02/01/2023
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Bruce E Sagan (bsagan@msu.edu)
We introduce a new partial order called the maximal chain descent order on the maximal chains of any finite, bounded poset with an ELlabeling. We prove that the maximal chain descent order encodes via its linear extensions all shellings of the order complex induced by the ELlabeling strictly including the wellknown lexicographic shellings. We show that the standard ELlabeling of the Boolean lattice has maximal chain descent order isomorphic to the type A weak order. We also prove that natural ELlabelings of intervals in Young's lattice give maximal chain descent orders isomorphic to partial orders on the standard Young tableaux or standard skew tableaux of a fixed shape given by swapping certain entries. We additionally show that the cover relations of maximal chain descent orders are generally more subtle than one might first expect, but we characterize the ELlabelings with the expected cover relations including many wellknown families of ELlabelings.

31558

Wednesday 2/1 3:00 PM

Igor Rapinchuk, MSU

Profinite groups and infinite Galois theory
 Igor Rapinchuk, MSU
 Profinite groups and infinite Galois theory
 02/01/2023
 3:00 PM  4:00 PM
 C329 Wells Hall
 Igor Rapinchuk (rapinchu@msu.edu)
No abstract available.

31560

Thursday 2/2 2:00 PM

Jie Yang, MSU

Potentially orthonormalizable modules
 Jie Yang, MSU
 Potentially orthonormalizable modules
 02/02/2023
 2:00 PM  3:00 PM
 C204A Wells Hall
 Jie Yang (yangji79@msu.edu)
I will discuss basics of potentially orthonormalizable modules and some related concepts, which are preliminaries for the theory of Fredholm's determinant of compact operators in nonarchimedean setting.

31553

Thursday 2/2 2:30 PM

James Murphy, Tufts University

ZOOM TALK (password the smallest prime > 100)  Towards Intrinsically LowDimensional Models in Wasserstein Space: Geometry, Statistics, and Learning
 James Murphy, Tufts University
 ZOOM TALK (password the smallest prime > 100)  Towards Intrinsically LowDimensional Models in Wasserstein Space: Geometry, Statistics, and Learning
 02/02/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
 Mark A Iwen ()
We consider the problems of efficient modeling and representation learning for probability distributions in Wasserstein space. We consider a general barycentric coding model in which data are represented as Wasserstein2 (W2) barycenters of a set of fixed reference measures. Leveraging the Riemannian structure of W2space, we develop a tractable optimization program to learn the barycentric coordinates when given access to the densities of the underlying measures. We provide a consistent statistical procedure for learning these coordinates when the measures are accessed only by i.i.d. samples. Our consistency results and algorithms exploit entropic regularization of the optimal transport problem, thereby allowing our barycentric modeling approach to scale efficiently. We also consider the problem of learning reference measures given observed data. Our regularized approach to dictionary learning in Wasserstein space addresses core problems of illposedness and in practice learns interpretable dictionary elements and coefficients useful for downstream tasks. Applications to image and natural language processing will be shown throughout the talk.

31535

Monday 2/6 4:00 PM

Aldo Garcia Guinto, MSU

Free Stein dimension of crossed products by finite groups
 Aldo Garcia Guinto, MSU
 Free Stein dimension of crossed products by finite groups
 02/06/2023
 4:00 PM  5:30 PM
 C517 Wells Hall
 Brent Nelson (banelson@msu.edu)
In this talk, we will discuss a free probabilistic quantity called free Stein dimension and compute it for a crossed product by a finite group. The free Stein dimension is the Murrayvon Neumann dimension of a particular subspace of derivations. Charlesworth and Nelson defined this quantity in the hope of finding a von Neumann algebra invariant. While it is still not known to be a von Neumann algebra invariant, it is an invariant for finitely generated unital tracial *algebras and algebraic methods have been more successful than analytic ones in studying it. Our result continues this trend, and reveals a formula for the free Stein dimension of a crossed product by a finite group that is reminiscint of the Schreier formula for a finite index subgroups of free groups.

31562

Tuesday 2/7 3:30 PM

Amitesh Datta, Princeton University

Does the Jones polynomial of a knot detect the unknot? A novel approach via braid group representations and class numbers of number fields.
 Amitesh Datta, Princeton University
 Does the Jones polynomial of a knot detect the unknot? A novel approach via braid group representations and class numbers of number fields.
 02/07/2023
 3:30 PM  4:30 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Peter Kilgore Johnson (john8251@msu.edu)
How good of an invariant is the Jones polynomial? The question is closely tied to studying braid group representations since the Jones polynomial can be defined as a (normalized) trace of a braid group representation.
In this talk, I will present my work developing a new theory to precisely characterize the entries of classical braid group representations, which leads to a generic faithfulness result for the Burau representation of B_4 (the faithfulness is a longstanding question since the 1930s and is equivalent to whether B_4 is a group of 3 x 3 matrices). In forthcoming work, I use this theory to furthermore explicitly characterize the Jones polynomial of all 3braid closures and generic 4braid closures. I will also describe my work which uses the class numbers of quadratic number fields to show that the Jones polynomial detects the unknot for 3braid links  this work also answers (in a strong form) a question of Vaughan Jones.
I will discuss all of the relevant background from scratch and illustrate my techniques through simple examples.

31563

Wednesday 2/8 3:00 PM

Wenjie Fang, Université Gustave Eiffel

Parabolic Tamari Lattices in Linear Type B
 Wenjie Fang, Université Gustave Eiffel
 Parabolic Tamari Lattices in Linear Type B
 02/08/2023
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Bruce E Sagan (bsagan@msu.edu)
We study parabolic aligned elements associated with the typeB Coxeter group and the socalled linear Coxeter element. These elements were introduced algebraically in (Mühle and Williams, 2019) for parabolic quotients of finite Coxeter groups and were characterized by a certain forcing condition on inversions. We focus on the typeB case and give a combinatorial model for these elements in terms of pattern avoidance. Moreover, we describe an equivalence relation on parabolic quotients of the typeB Coxeter group whose equivalence classes are indexed by the aligned elements. We prove that this equivalence relation extends to a congruence relation for the weak order. The resulting quotient lattice is the typeB analogue of the parabolic Tamari lattice introduced for type A in (Mühle and Williams, 2019). These lattices have not appeared in the literature before. As work in progress, we will also talk about various combinatorial models and bijections between them. Joint work with Henri Mühle and JeanChristophe Novelli.

31567

Wednesday 2/8 3:00 PM

Igor Rapinchuk, MSU

Profinite groups and infinite Galois theory
 Igor Rapinchuk, MSU
 Profinite groups and infinite Galois theory
 02/08/2023
 3:00 PM  4:00 PM
 C329 Wells Hall
 Igor Rapinchuk (rapinchu@msu.edu)
No abstract available.

31539

Wednesday 2/8 3:00 PM

Yier Lin, University of Chicago

Some recent progress in the weak noise theory of the KPZ equation
 Yier Lin, University of Chicago
 Some recent progress in the weak noise theory of the KPZ equation
 02/08/2023
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Konstantin Matetski (matetski@msu.edu)
In this talk, we will study the Freidlin–Wentzell LDP for the KPZ equation using the variational principle. Such an approach goes under the name of the weak noise theory in physics. We will explain how to extract various limits of the most probable shape of the KPZ equation in the setting of the Freidlin–Wentzell LDP. Some future directions will also be discussed at the end. The talk is based on several joint works with Pierre Yves Gaudreau Lamarre and LiCheng Tsai.

31564

Wednesday 2/8 4:10 PM

Alexander Volberg, MSU

Noncommutative BohnenblustHille inequalities and application to learning the quantum observables
 Alexander Volberg, MSU
 Noncommutative BohnenblustHille inequalities and application to learning the quantum observables
 02/08/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Willie WaiYeung Wong (wongwil2@msu.edu)
BohnenblustHille inequalities for Boolean cubes have been proven with dimensionfree constants that grow subexponentially in the degree (Defant—Mastylo—Peres). Such inequalities have found great applications in learning low degree Boolean functions (Eskenazis—Ivanisvili). Motivated by learning quantum observables, a quantum counterpart of BohnenblustHille inequality for Boolean cubes was recently conjectured in Cambyse Rouz\’e, Melchior Wirth, and Haonan Zhang: ``Quantum Talagrand, KKL and Friedgut’s theorems and the learnability of quantum Boolean functions.” arXiv preprint, arXiv:2209.07279, 2022.
Haonan Zhang and myself prove such noncommutative BohnenblustHille inequalities with constants that are dimensionfree and of exponential growth in the degree. As applications, we study learning problems of quantum observables.
(Speaker will present remotely)

31561

Thursday 2/9 11:00 AM

Andy Krause, MSU

AI, ChatGPT, and Teaching
 Andy Krause, MSU
 AI, ChatGPT, and Teaching
 02/09/2023
 11:00 AM  12:00 PM
 D101 Wells Hall
 Tsvetanka Sendova (tsendova@msu.edu)
No abstract available.

31568

Thursday 2/9 2:10 PM

Peikai Qi, MSU

Banach space over Qp
 Peikai Qi, MSU
 Banach space over Qp
 02/09/2023
 2:10 PM  3:10 PM
 C204A Wells Hall
 Peikai Qi (qipeikai@msu.edu)
No abstract available.

31569

Thursday 2/9 2:30 PM

Elizabeth Munch, MSU

ZOOM TALK (password the smallest prime > 100)  Combining network analysis and persistent homology for classifying behavior of time series
 Elizabeth Munch, MSU
 ZOOM TALK (password the smallest prime > 100)  Combining network analysis and persistent homology for classifying behavior of time series
 02/09/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Mark A Iwen (iwenmark@msu.edu)
Persistent homology, the flagship method of topological data analysis, can be used to provide a quantitative summary of the shape of data. One way to pass data to this method is to start with a finite, discrete metric space (whether or not it arises from a Euclidean embedding) and to study the resulting filtration of the Rips complex. In this talk, we will discuss several available methods for turning a time series into a discrete metric space, including the Takens embedding, $k$nearest neighbor networks, and ordinal partition networks. Combined with persistent homology and machine learning methods, we show how this can be used to classify behavior in time series in both synthetic and experimental data.

31566

Thursday 2/9 3:00 PM

Fan Yang, Michigan State University

Foliations and transverse invariant measures from a dynamical systems point of view
 Fan Yang, Michigan State University
 Foliations and transverse invariant measures from a dynamical systems point of view
 02/09/2023
 3:00 PM  4:00 PM
 C117 Wells Hall
 Fan Yang (yangfa31@msu.edu)
In this talk, we will discuss foliations and their transverse invariant measures (i.e., measures on crosssections that are invariant under the holonomy maps) from a dynamical systems point of view. We will show that for a large family of diffeomorphisms, the unstable foliations admit families of transverse measures that are naturally related to certain probability measures invariant under the dynamics. Given an unstable leaf, we will consider a dynamically defined average that captures its intersection with crosssections and prove that this averaging will converge exponentially fast to the transverse invariant measures. This is a joint work with Ures, Viana and J. Yang.

31523

Monday 2/13 3:00 PM

Keerthi Madapusi Pera, Boston College

Derived cycles on Shimura varieties
 Keerthi Madapusi Pera, Boston College
 Derived cycles on Shimura varieties
 02/13/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Georgios Pappas (pappasg@msu.edu)
I’ll explain how methods from derived algebraic geometry can be applied to give a uniform definition of special cycle classes on integral models of Shimura varieties of Hodge type, verifying some consequences of Kudla’s conjectures on the modularity of generating series of cycles on Shimura varieties of Hermitian type.

31504

Tuesday 2/14 2:00 PM

Renaud Detcherry, Institut de Mathématiques de Bourgogne

Title: On the kernel of WittenReshetikhinTuraev quantum representations
 Renaud Detcherry, Institut de Mathématiques de Bourgogne
 Title: On the kernel of WittenReshetikhinTuraev quantum representations
 02/14/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Efstratia Kalfagianni (kalfagia@msu.edu)
Abstract: WittenReshetikhinTuraev SO(3) quantum representations are a family of representations of mapping class groups of surfaces. The family is asymptotically faithful, but each representation has kernel: indeed, rth powers of Dehn twists are in the kernel of the level r quantum representation.
An open question is whether the kernel is generated by rth powers of Dehn twists; we will present partial results on this question, by relating the socalled "hadic expansion" of quantum representations to Johnson homomorphisms.

31574

Wednesday 2/15 3:00 PM

Frank Sottile, Texas A&M Univeristy

A MurnaghanNakayama formula in quantum Schubert calculus
 Frank Sottile, Texas A&M Univeristy
 A MurnaghanNakayama formula in quantum Schubert calculus
 02/15/2023
 3:00 PM  3:50 PM
 C517 Wells Hall
 Bruce E Sagan (bsagan@msu.edu)
The MurnaghanNakayama formula expresses the product of a
Schur function with a Newton power sum in the basis of Schur
functions. An important generalization of Schur functions are
Schubert polynomials (both classical and quantum). For these, a
MurnaghanNakayama formula is geometrically meaningful. In
previous work with Morrison, we established a MurnaghanNakayama
formula for Schubert polynomials and conjectured a quantum
version. In this talk, I will discuss some background and then
some recent work proving this quantum conjecture. This is joint
work with Benedetti, Bergeron, Colmenarejo, and Saliola.

31556

Tuesday 2/21 2:00 PM

Ian Montague , Brandeis University

TBA
 Ian Montague , Brandeis University
 TBA
 02/21/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
No abstract available.

31570

Thursday 2/23 2:30 PM

Yufeng Liu, University of North Carolina at Chapel Hill

ZOOM TALK (password the smallest prime > 100)  TBA
 Yufeng Liu, University of North Carolina at Chapel Hill
 ZOOM TALK (password the smallest prime > 100)  TBA
 02/23/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Mark A Iwen ()
No abstract available.

30460

Thursday 2/23 4:10 PM

Brendan Hassett, Brown University

TBA
 Brendan Hassett, Brown University
 TBA
 02/23/2023
 4:10 PM  5:00 PM
 Online (virtual meeting)
 Joseph Waldron (waldro51@msu.edu)
No abstract available.

29395

Friday 2/24 4:00 PM

Yuehaw Khoo, U Chicago

TBA
 Yuehaw Khoo, U Chicago
 TBA
 02/24/2023
 4:00 PM  5:00 PM
 C304 Wells Hall
 Mark A Iwen (iwenmark@msu.edu)
TBA

31532

Monday 2/27 3:00 PM

Michail Savvas, University of Texas

TBA
 Michail Savvas, University of Texas
 TBA
 02/27/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Francois Greer (greerfra@msu.edu)
No abstract available.

31547

Tuesday 2/28 2:00 PM

Ryan Stees, Indiana University

TBA
 Ryan Stees, Indiana University
 TBA
 02/28/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
No abstract available.

31544

Wednesday 3/1 3:00 PM

Andrei Prokhorov, University of Michigan

TBA
 Andrei Prokhorov, University of Michigan
 TBA
 03/01/2023
 3:00 PM  3:50 PM
 C405 Wells Hall
 Konstantin Matetski (matetski@msu.edu)
TBA

31571

Thursday 3/2 2:30 PM

Yuejie Chi, Carnegie Mellon University

ZOOM TALK (password the smallest prime > 100)  TBA
 Yuejie Chi, Carnegie Mellon University
 ZOOM TALK (password the smallest prime > 100)  TBA
 03/02/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Mark A Iwen ()
No abstract available.

29375

Thursday 3/2 4:10 PM

Katy Craig, UCSB

TBA
 Katy Craig, UCSB
 TBA
 03/02/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Olga Turanova (turanova@msu.edu)
TBA

30471

Monday 3/13 3:00 PM

Ivan Loseu, Yale University

TBA
 Ivan Loseu, Yale University
 TBA
 03/13/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Igor Rapinchuk (rapinchu@msu.edu)
No abstract available.

31573

Tuesday 3/14 2:00 PM

Shunyu Wan , University of Virginia

TBA
 Shunyu Wan , University of Virginia
 TBA
 03/14/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
No abstract available.

29404

Thursday 3/16 4:10 PM

John Baldwin, Boston College

TBA
 John Baldwin, Boston College
 TBA
 03/16/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Joseph Waldron (waldro51@msu.edu)
No abstract available.

31533

Friday 3/17 4:00 PM

Terry Haut, Lawerence Livermore National Lab

TBA
 Terry Haut, Lawerence Livermore National Lab
 TBA
 03/17/2023
 4:00 PM  5:00 PM
 C304 Wells Hall
 Mark A Iwen ()
TBA

31526

Monday 3/20 3:00 PM

John Sheridan, Princeton University

TBA
 John Sheridan, Princeton University
 TBA
 03/20/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Francois Greer (greerfra@msu.edu)
No abstract available.

31538

Tuesday 3/21 2:00 PM

Anup Poudel, Ohio State

TBA
 Anup Poudel, Ohio State
 TBA
 03/21/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Vijay B Higgins (higgi231@msu.edu)
TBA

30461

Wednesday 3/22 4:10 PM

Katrina Morgan, Northwestern University

TBA
 Katrina Morgan, Northwestern University
 TBA
 03/22/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Willie WaiYeung Wong (wongwil2@msu.edu)
TBA

29388

Sunday 3/26 4:10 PM

Robin Walters, Northeastern University

TBA
 Robin Walters, Northeastern University
 TBA
 03/26/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Olga Turanova (turanova@msu.edu)
TBA

29381

Thursday 3/30 4:10 PM

Tim Hoheisel, McGill University

TBA
 Tim Hoheisel, McGill University
 TBA
 03/30/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Olga Turanova (turanova@msu.edu)
TBA

31554

Tuesday 4/4 2:00 PM

David Chan, Vanderbilt University

TBA
 David Chan, Vanderbilt University
 TBA
 04/04/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
No abstract available.

29400

Wednesday 4/5 4:10 PM

Matt Jacobs, Purdue

TBA
 Matt Jacobs, Purdue
 TBA
 04/05/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Olga Turanova (turanova@msu.edu)
TBA

29382

Thursday 4/6 4:10 PM

Michael Brannan, University of Waterloo

TBA
 Michael Brannan, University of Waterloo
 TBA
 04/06/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Olga Turanova (turanova@msu.edu)
TBA

31543

Monday 4/10 2:00 PM

Sam Gunningham, Montana State

RTG Seminar: TBA
 Sam Gunningham, Montana State
 RTG Seminar: TBA
 04/10/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Vijay B Higgins (higgi231@msu.edu)
TBA

31542

Tuesday 4/11 2:00 PM

Sam Gunningham, Montana State

TBA
 Sam Gunningham, Montana State
 TBA
 04/11/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Vijay B Higgins (higgi231@msu.edu)
TBA

29385

Wednesday 4/12 4:10 PM

Leonardo Abbrescia, Vanderbilt University

A localized picture of the maximal development for shock forming solutions of the 3D compressible Euler equations
 Leonardo Abbrescia, Vanderbilt University
 A localized picture of the maximal development for shock forming solutions of the 3D compressible Euler equations
 04/12/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Willie WaiYeung Wong (wongwil2@msu.edu)
Understanding the behavior of solutions to the compressible Euler equations for large times necessitates a sharp analysis of possible singularities that can form. Our understanding of shock singularities in three space dimensions has enjoyed a dramatic surge in progress in the past two decades due in part to the mathematical techniques that were developed to study Einstein’s equations. In this talk, I will discuss my recent work which provides a sharp localized description of a shock singularity as part of the boundary of maximal development of smooth data. The set of Cartesian spacetime points on which a singularity occurs, which we call the singular boundary $\mathcal{B}$, has the structure of an embedded hypersurface with very degenerate causal properties. I will give an overview of the difficulties that occur in the construction of the singular boundary, and if time permits, also discuss the construction of the Cauchy horizon which emanates from the past boundary of $\mathcal{B}$.

30453

Thursday 4/13 4:10 PM

David Fisher, Indiana University Bloomington

TBA
 David Fisher, Indiana University Bloomington
 TBA
 04/13/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Olga Turanova (turanova@msu.edu)
TBA

31548

Monday 4/17 2:00 PM

Siddhi Krishna, Columbia University

RTG Seminar: TBA
 Siddhi Krishna, Columbia University
 RTG Seminar: TBA
 04/17/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
No abstract available.

31545

Monday 4/17 3:00 PM

Olivier Martin, Stony Brook University

TBA
 Olivier Martin, Stony Brook University
 TBA
 04/17/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Francois Greer (greerfra@msu.edu)
No abstract available.

31549

Tuesday 4/18 2:00 PM

Siddhi Krishna, Columbia University

TBA
 Siddhi Krishna, Columbia University
 TBA
 04/18/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
No abstract available.

29405

Thursday 4/20 4:10 PM

Robert Pollack, Boston University

TBA
 Robert Pollack, Boston University
 TBA
 04/20/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Joseph Waldron (waldro51@msu.edu)
No abstract available.

31505

Friday 4/21 3:00 PM

Jaclyn Lang, Temple

TBA (note unusual day)
 Jaclyn Lang, Temple
 TBA (note unusual day)
 04/21/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Preston Wake (wakepres@msu.edu)
No abstract available.

31534

Friday 4/21 4:00 PM

Guosheng Fu, University of Notre Dame

Highorder variational Lagrangian schemes for compressible fluids
 Guosheng Fu, University of Notre Dame
 Highorder variational Lagrangian schemes for compressible fluids
 04/21/2023
 4:00 PM  5:00 PM
 C304 Wells Hall
 Mark A Iwen ()
We present a class of highorder variational Lagrangian schemes for compressible fluids using the tool of energetic variational approach (EnVarA). This is the first time that the EnVarA framework has been applied to non isothermal models where temperature effects are nonnegligible. We illustrate the main idea using the classical ideal gas model, and construct variational Lagrangian schemes that are conservative and entropy stable using EnVarA. Efficient implicit time stepping is designed so that the time step size is not restricted by the sound speed and the model is robust in the low Mach number case. Ample numerical examples will be presented to show the good performance of the proposed schemes for problems including strong shocks, low Mach number flows and multimaterial flows. This is a joint work with Prof. Chun Liu from IIT.

31537

Monday 4/24 2:00 PM

Sarah Petersen, University of Colorado, Boulder

RTG Seminar: TBA
 Sarah Petersen, University of Colorado, Boulder
 RTG Seminar: TBA
 04/24/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
No abstract available.

29398

Monday 4/24 3:00 PM

Ján Mináč, University of Western Ontario

TBA
 Ján Mináč, University of Western Ontario
 TBA
 04/24/2023
 3:00 PM  4:00 PM
 Online (virtual meeting)
 Preston Wake (wakepres@msu.edu)
No abstract available.

31575

Tuesday 4/25 10:30 AM

Alex Bols, Caltech

TBA
 Alex Bols, Caltech
 TBA
 04/25/2023
 10:30 AM  11:30 AM
 C304 Wells Hall
 Jeffrey Hudson Schenker (schenke6@msu.edu)
No abstract available.

31536

Tuesday 4/25 2:00 PM

Sarah Petersen, University of Colorado, Boulder

TBA
 Sarah Petersen, University of Colorado, Boulder
 TBA
 04/25/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
No abstract available.

30452

Wednesday 4/26 4:10 PM

Yakov ShlapentokhRothman, University of Toronto

TBA
 Yakov ShlapentokhRothman, University of Toronto
 TBA
 04/26/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Willie WaiYeung Wong (wongwil2@msu.edu)
TBA

29406

Thursday 4/27 4:10 PM

Tony Feng, University of California, Berkeley

TBA
 Tony Feng, University of California, Berkeley
 TBA
 04/27/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Joseph Waldron (waldro51@msu.edu)
No abstract available.

31541

Friday 4/28 4:00 PM

Yulong Xing, Ohio State University

TBA
 Yulong Xing, Ohio State University
 TBA
 04/28/2023
 4:00 PM  5:00 PM
 C304 Wells Hall
 Mark A Iwen ()
TBA
